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About the Lecture

The lecture Biostatistics and Epidemiology Question Set 2 by Lecturio USMLE is from the course Biostatistics and Epidemiology – Board-Style Questions.

Included Quiz Questions

A researcher was studying the association between haemoglobin value and BMI. He divided the students of a class into two groups based on their BMIs into normal weight group and overweight group. Then he measured the haemoglobin values of all the students. His null hypothesis was that there is no association between haemoglobin value and body weight. The mean haemoglobin value of the normal weight group was 13.4 gm/dl and that of the overweight group was 13.8 gm/dl. He obtained a mean difference of 0.4 gm/dl between the two groups. He did an unpaired t test and he got a p value of 0.10. What does this mean?

If the null hypothesis is true, there is a 10% probability to get this difference of 0.4 gm/dl or higher, due to chance.

If the null hypothesis is not true, 10% or higher , of the students still do not show any association between haemoglobin value and weight.

If the null hypothesis is true, there is a 10% probability to get this difference of 0.4 gm/dl due to chance.

If the null hypothesis is true, there is still a 10% probability not to get this difference of 0.4 gm/dl or higher, due to chance.

If the null hypothesis is not true, there is still a 10% probability not to get this difference of 0.4 gm/dl or higher, due to chance.

In a study to find out the association between smoking and bladder cancer, 100 adult males with bladder cancer were recruited to the study group. The control group consisted of 100 similar individuals without bladder cancer. Their history of smoking was obtained and the data was analysed. The calculated odds ratio was 2.7. What does this mean?

Odds of smoking, in bladder cancer patients, were 2.7 times to that of those without bladder cancer.

The smokers had 2.7 times increased risk of developing bladder cancer when compared to those who do not smoke.

Bladder cancer patients had 2.7 times increased risk of smoking when compared to those without bladder cancer.

Odds of smoking in bladder cancer patients were 2.7 times higher when compared to those who do not smoke.

Odds of smoking was 2.7 times higher in those patients who had a risk of developing bladder cancer in future.

In a study for determining the risk factors of young age myocardial infarction (MI), 30 cases of young age MI were recruited to the study group. 60 suitable individuals were recruited to the control group. Educational status was considered as an important variable as it would affect the awareness about the disease and its risk factors. Education status data was taken qualitatively in four categories and then later recoded to two new categories, namely low education and high education. A chi square test was done to test the significance and the risk was also obtained as Odds ratio of 2.1 for the low education category with a confidence interval of 0.9 to 9.7. What inference do you make on the association between young age myocardial infarction and educational status with this study?

The association is not statistically significant and low education is not a risk factor.

The association is not statistically significant but low education is a risk factor.

The association is statistically significant but low education is not a risk factor.

The association is statistically significant and low education is a risk factor.

Cannot comment as the p value is not given.

A researcher faced a task of calculating the mean height of the male students in a college having 2000 male students and 1750 female students. The mean height of the sample was obtained as 176 cm with a standard deviation of 7 cm. The researcher calculated a confidence interval for the mean height of the male students in that college. What more do you need to calculate the same?

Total sample size of the study

The mean height of the male students in that college

Total number of male students in that college who did not take part in the study

A sampling frame of all the male students in the college

Given data is adequate and no more data is needed.

A 52-year-old male presents to the office for Diabetes follow-up. He is currently controlling his diabetes through lifestyle modification only. He monitors his blood glucose at home with a glucometer. He gives the doctor a list of his most recent early morning fasting glucose readings from the past 8 days which are- 128 mg/dl, 130 mg/dl, 132 mg/dl, 125 mg/dl, 134 mg/dl, 127 mg/dl, 128 mg/dl and 136 mg/dl. Which value most likely corresponds with the median of this data set?

129 mg/dl

127 mg/dl

128 mg/dl

130 mg/dl

132 mg/dl

A 21-year-old male comes to the office for a follow-up visit. He was recently diagnosed with Type I Diabetes Mellitus after being hospitalized for diabetic ketoacidosis following a respiratory infection. He is here today to discuss treatment options available for his condition. The doctor mentions a recent study, in which researchers have developed a new version of the insulin pump that appears efficacious in Type I Diabetics. They are currently comparing it to insulin injection therapy. This new pump is not yet available but looks very promising. At what stage of clinical trials is this current treatment most likely at?

Phase 3

Phase 2

Phase 1

Phase 0

Phase 4

A 42-year-old male presents to the office for hypertension follow-up. He was recently diagnosed with hypertension and is here to discuss management plans with his primary care provider. The doctor mentions that a recent study where the effect of a healthy lifestyle education program on blood pressure was studied in two matched, rural communities, where one community received health education program and the other did not. What is the type of study most likely being described here?

Community Trial

Crossover Study

Explanatory Study

Case-Control Trial

Cross-sectional Study

Researchers are studying the effects of a new medication for treatment of Type II Diabetes. A randomized group of 100 subjects is given the new medication first for a period of two months followed by a washout period of two weeks and the administration of the gold standard medication for a period of two months. Another randomized group of 100 subjects is be given the gold standard medication first for a period of two months followed by a washout period of two weeks and the administration of the new medication for a period of two months. What is the main disadvantage of this study design?

Carryover effect

Increasing selection bias

Hawthorne effect

Increasing confounding bias

Decreasing power

Author of lecture Biostatistics and Epidemiology Question Set 2

Lecturio USMLE

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